Battery monitoring and control integrated circuit and battery system

ABSTRACT

A battery monitoring and control integrated circuit is connected to a cell group having a plurality of series-connected single cells for monitoring and controlling the single cells, and includes: a first start input terminal for connecting to a DC signal generation circuit which generates a DC signal based on an AC start signal input from the outside; a start detection unit which detects the DC signal and activates the battery monitoring and control integrated circuit; and a start output unit which outputs the AC start signal to the outside after the activation of the battery monitoring and control integrated circuit.

TECHNICAL FIELD

The present invention relates to a battery monitoring and controlintegrated circuit and a battery system including the battery monitoringand control integrated circuit.

BACKGROUND ART

An assembled battery (battery system) configured by connecting aplurality of secondary single cells in series is used for a hybridelectric vehicle (HEV), an electric vehicle (EV), or the like to securea desired high voltage. Such an assembled battery uses a control ICwhich monitors the states of the single cells and controls the states ofcharge and discharge, and a battery controller which controls thecontrol IC to manage each single cell (see PTL 1).

In the battery system of PTL 1, four single cells constitute one batterycell group, and a control IC is connected to each battery cell group. Acontrol IC at the highest level connected to a battery cell group on thehighest potential side is activated in response to a start signal fromthe battery controller, and outputs, to a control IC one level below,the start signal at a voltage in accordance with the potential of abattery cell group corresponding to the control IC one level below. Suchan operation is performed sequentially from a control IC at a higherlevel to a control IC at a lower level to activate all the control ICs.

CITATION LIST Patent Literature

PTL 1: JP 2005-318750 A

SUMMARY OF INVENTION Technical Problem

At the activation of the battery system, each control IC but a controlIC at the highest level is fed a start signal at a higher voltage thanits operating power supply from another control IC at a higher level.Therefore, it is necessary for each control IC to be provided withspecial circuits for inputting/outputting a start signal, such as adedicated interface circuit and a protection circuit, to enable a normaloperation even if such a start signal is input.

Solution to Problem

A battery monitoring and control integrated circuit according to a firstaspect of the present invention is connected to a cell group having aplurality of series-connected single cells for monitoring andcontrolling the single cells, and includes: a first start input terminalfor connecting to a DC signal generation circuit which generates a DCsignal based on an AC start signal input from the outside; a startdetection unit which detects the DC signal and activates the batterymonitoring and control integrated circuit; and a start output unit whichoutputs the AC start signal to the outside after the activation of thebattery monitoring and control integrated circuit.

According to a second aspect of the present invention, it is preferredin the battery monitoring and control integrated circuit of the firstaspect that the DC signal generation circuit be a doubler rectifiercircuit.

According to a third aspect of the present invention, it is morepreferred in the battery monitoring and control integrated circuit ofthe second aspect that the doubler rectifier circuit include arectifying element built in the battery monitoring and controlintegrated circuit.

According to a fourth aspect of the present invention, the batterymonitoring and control integrated circuit of any of the first to thirdaspects may further include a second start input terminal for inputtinga DC start signal input from the outside. It is preferred in the batterymonitoring and control integrated circuit that the DC start signal inputinto the second start input terminal be input into the start detectionunit not via the DC signal generation circuit.

A battery system according to a fifth aspect of the present inventionincludes a plurality of cell groups each having a plurality ofseries-connected single cells; a plurality of battery monitoring andcontrol integrated circuits which is respectively connected to theplurality of cell groups and monitors and controls the single cells ofthe cell groups; and a battery controller which controls the pluralityof battery monitoring and control integrated circuits. It is preferredin the battery system that the plurality of battery monitoring andcontrol integrated circuits be connected to each other via capacitors ina predetermined communication order. Moreover, it is preferred that theplurality of battery monitoring and control integrated circuits eachinclude: a first start input terminal for connecting to a DC signalgeneration circuit which generates a DC signal based on an AC startsignal input from the battery controller or a battery monitoring andcontrol integrated circuit at a higher level in the communication order;a start detection unit which detects the DC signal and activates thebattery monitoring and control integrated circuit; and a start outputunit which outputs the AC start signal to a battery monitoring andcontrol integrated circuit at a lower level in the communication orderor the battery controller after the activation of the battery monitoringand control integrated circuit.

According to a sixth aspect of the present invention, it is preferred inthe battery system of the fifth aspect that the DC signal generationcircuit be a doubler rectifier circuit.

According to a seventh aspect of the present invention, it is morepreferred in the battery system of the sixth aspect that the doublerrectifier circuit include a rectifying element built in the batterymonitoring and control integrated circuit.

According to an eighth aspect of the present invention, in the batterysystem of any of the fifth to seventh aspects, the plurality of batterymonitoring and control integrated circuits may each further include asecond start input terminal for inputting a DC start signal input fromthe battery controller. It is preferred in the battery system that theDC start signal input into the second start input terminal be input intothe start detection unit not via the DC signal generation circuit.

Advantageous Effects of Invention

According to the invention, the need of special circuits forinputting/outputting a start signal can be eliminated in a batterymonitoring and control integrated circuit which monitors and controls abattery.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of a hybridelectric vehicle including a battery system according to the presentinvention.

FIG. 2 is a diagram illustrating an example of communication connectionbetween integrated circuits 300 in a cell controller 200 and amicrocomputer 504 in a battery controller 500 according to the presentinvention.

FIG. 3 is a diagram illustrating an example of communication connectionbetween the integrated circuits 300 in the cell controller 200 and themicrocomputer 504 in the battery controller 500 according to aconventional example.

FIG. 4 is a diagram illustrating an internal configuration example ofthe integrated circuit 300 according to the present invention.

FIG. 5 is a diagram illustrating an internal configuration example ofthe integrated circuit 300 according to the conventional example.

FIG. 6 is a diagram illustrating a detailed example of communicationconnection between an integrated circuit 300 a on the lowest potentialside, an integrated circuit 300 b one level above the integrated circuit300 a in the potential order, and the microcomputer 504.

FIG. 7 is a diagram illustrating the detailed example of communicationconnection between an integrated circuit 300 d on the highest potentialside, an integrated circuit 300 c one level below the integrated circuit300 d in the potential order, and the microcomputer 504.

FIG. 8 is a diagram illustrating a part related to a communication pathof an AC start signal between the integrated circuits 300 a and 300 b ina readily understandable manner.

FIG. 9 is an equivalent circuit diagram corresponding to a cell groupconnected to diodes 216, a capacitor 403, a capacitor 406, and theintegrated circuit 300 a.

FIG. 10 is a diagram illustrating a voltage waveform example of arectangular wave signal output from a start output terminal WU_Tx of theintegrated circuit 300 a, and a DC voltage applied to a start detectionunit 215 of the integrated circuit 300 b.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention is hereinafter described withreference to the drawings. The embodiment described below is an examplewhere the present invention is applied to a battery system used for ahybrid electric vehicle (HEV) or the like. The present invention can bewidely applied to various battery systems to be mounted on a plug-inhybrid electric vehicle (PHEV), an electric vehicle (EV), a railwayvehicle, and the like, not limited to HEV.

In the following example, a lithium-ion battery having voltage within arange of 3.0 to 4.2 V (average output voltage: 3.6 V) is assumed to bean electric storage/discharge device as a minimum unit of control.However, the electric storage/discharge device may be, other than thelithium-ion battery, any electricity storable and dischargeable devicewhich controls its use if the SOC (State of Charge) is too high(overcharge) or too low (over-discharge). Here, it is collectivelycalled an electric cell or a single cell.

In the embodiment described below, a plurality of (roughly several to adozen or so) single cells connected in series is called a cell group. Aplurality of the cell groups connected in series is called a batterymodule. Furthermore, a plurality of the cell groups or battery modulesconnected in series or series-parallel is designated as an assembledbattery. Each cell group is provided with an integrated circuit whichdetects the cell voltage of each single cell, and monitors and controlsthe battery status while performing a balancing operation and the like.

Firstly, a description is given of an example where the battery systemaccording to the present invention is applied to a drive system for ahybrid electric vehicle with reference to FIG. 1. FIG. 1 is a diagramillustrating a configuration example of a hybrid electric vehicleincluding the battery system according to the present invention.

A battery system 100 is connected to an inverter 700 via relays 600 and610. The inverter 700 is connected to a motor 800. At the start oracceleration of the vehicle, the battery system 100 supplies dischargepower through the inverter 700 to the motor 800 to assist anunillustrated engine. At the stop or deceleration of the vehicle, thebattery system 100 is charged with the regenerated power from the motor800 through the inverter 700. The inverter 700 includes an invertercircuit having a plurality of semiconductor switching elements, a gatedriving circuit for the semiconductor switching element, and a motorcontroller which generates a pulse signal to perform PWM control on thegate driving circuit. However, they are omitted in FIG. 1

The battery system 100 is mainly configured by an assembled battery 102constituted by a plurality of single cells 101 being lithium-ionbatteries, a cell controller 200 including a plurality of batterymonitoring and control integrated circuits 300 which detects voltages ofthe single cells 101 on a cell group basis and performs a balancingdischarge operation and the like, and a battery controller 500 whichcontrols the operation of the cell controller 200 and determines thestates of the single cells 101. In the example of the battery system 100illustrated in the embodiment, 96 series-connected lithium-ion batterieswith a rated capacity of 5.5 Ah are used as the single cells 101. Thebattery controller 500 communicates with the plurality of integratedcircuits 300 via an insulating element group 400 and controls theplurality of integrated circuits 300. The integrated circuit 300 isprovided for each cell group as described above. A voltage detectionline between the assembled battery 102 and the cell controller 200 isconnected by an unillustrated connector to the cell controller 200.

The battery controller 500 includes a total voltage detection circuit501 which measures the total voltage of the assembled battery 102, acharge/discharge current detection circuit 502 which is connected to acurrent sensor 503 for detecting a charge/discharge current flowingthrough the assembled battery 102, and a microcomputer 504 whichcommunicates with the cell controller 200, the inverter 700, and anunillustrated high-level vehicle controller, and controls the entirebattery controller 500. The total voltage detection circuit 501 does notneed to be provided inside the battery controller 500 as in FIG. 1 aslong as the total voltage of the assembled battery 102 can be measured.

A total voltage detection circuit 701 which detects the total voltage ofthe assembled battery 102 is also provided inside the inverter 700.Moreover, although not illustrated in FIG. 1, the battery controller 500makes a temperature correction of the parameter of the battery statusbased on the temperature of the single cell 101 measured by atemperature detection circuit connected to the integrated circuit 300.

Although omitted in FIG. 1, the cell controller 200 and the batterycontroller 500 are provided on one board, and housed in a metal case.Moreover, the assembled battery 102 is also housed in a metal case. Thecell controller 200 and the assembled battery 102 are connected by aharness in which a plurality of voltage detection lines, a connectionline of a temperature sensor (not illustrated) of the single cell 101,and the like are tied in a bundle.

The following operations are performed after the activation of thebattery system 100. The battery controller 500 transmits an instructionto measure the OCV (open circuit voltage) of the single cells 101 to thecell controller 200 via the insulating element group 400. Data on theOCV of the single cells 101 measured on the instruction is transmittedon a cell group basis from the cell controller 200 to the batterycontroller 500 via the insulating element group 400.

The battery controller 500 converts the received OCV of the single cells101 into the SOC, and calculates the deviations of the SOC of the singlecells 101. The single cell 101 having the deviation of the SOC largerthan a predetermined value is targeted for balancing discharge. The timerequired until the deviation of the SOC of the single cell 101 targetedfor balancing discharge becomes zero is calculated. An instruction toperform a control operation to turn on a balancing switch in theintegrated circuit 300 only during this time is transmitted from thebattery controller 500 to the cell controller 200. The cell controller200 performs balancing discharge on the balancing-target single cell 101on the instruction.

After the SOC of the assembled battery 102 is calculated from the OCV ofthe single cells 101 measured above, the inverter 700 or the vehiclecontroller (not illustrated) being the high-level controller turns onthe relays 600 and 610. The battery system 100 is connected to theinverter 700 and the motor 800. If the inverter 700 receives acharge/discharge instruction from the vehicle controller, then theinverter 700 operates to drive the motor 800 and the charge/dischargeoperation of the battery system 100 is performed.

After the time when the relays 600 and 610 are turned on and the batterysystem 100 starts charging/discharging, the battery controller 500 usesthe total voltage detection circuit 501 and the charge/discharge currentdetection circuit 502 to measure the total voltage and thecharge/discharge current at every predetermined time interval. Thebattery controller 500 calculates the state of charge (SOC) and internalresistance (DCR) of the assembled battery 102 in real time from theobtained values of the total voltage and the charge/discharge current.Furthermore, an electric current or electric power with which theassembled battery 102 can be charged or discharged is calculated fromthese values in real time and transmitted to the inverter 700. Theinverter 700 controls the charge/discharge current or electric powerwithin a range of the current or power.

FIG. 2 is a diagram illustrating an example of communication connectionbetween integrated circuits 300 a to 300 d in the cell controller 200and the microcomputer 504 in the battery controller 500 according to thepresent invention. The integrated circuits 300 a to 300 d of FIG. 2correspond to the integrated circuits 300 of FIG. 1.

The microcomputer 504 includes a start signal output port for outputtinga start signal to activate the integrated circuits 300 a to 300 d in thecell controller 200, a data transmission port TXD for transmitting acommand and data, and an FF signal output port for outputting a datapacket (an FF signal) to detect the overcharge state.

The example of FIG. 2 has a configuration in which two battery moduleseach having two series-connected cell groups each having the pluralityof single cells 101 connected in series are arranged, one each above andbelow a service disconnect switch (SD-SW) 103. The number of the cellgroups configuring the battery module is not limited to two but may bethree or more. The integrated circuits 300 a to 300 d are provided,corresponding respectively to the cell groups. If simply referred to asthe integrated circuit 300 in the following, the integrated circuits 300a to 300 d are not particularly specified.

The SD-SW 103 is a switch usually used in a high voltage assembledbattery or the like. The SD-SW 103 is opened at the time of amaintenance check to block a current path of the assembled battery 102and prevent workers from electrical shock. If the SD-SW 103 is opened,the series connection between the battery modules is cut off.Accordingly, even if a person touches the highest and lowest terminalsof the assembled battery 102, his/her body is not subjected to highvoltage. Therefore, electrical shock can be prevented.

On a communication line of a command and a data signal, a command and adata signal are transmitted from the data transmission port TXD of themicrocomputer 504 through a high-speed insulating element 401 to acommunication receiving terminal RXD of the integrated circuit 300 acorresponding to the cell group on the lowest potential side in theassembled battery 102. On the other hand, on a communication line of astart signal, a start signal is transmitted from the start signal outputport of the microcomputer 504 through a low-speed insulating element 402to a DC start signal input terminal WU_Rx of the integrated circuit 300a. Moreover, on a communication line of an FF signal, an FF signal istransmitted from the FF signal output port of the microcomputer 504through the low-speed insulating element 402 to an FF input terminalFFIN of the integrated circuit 300 a.

A communication output terminal TXD of the integrated circuit 300 acorresponding to the cell group on the lowest potential side isconnected via the capacitor 403 to a communication receiving terminalRXD of the integrated circuit 300 b corresponding to the cell group onelevel above in the potential order. Moreover, an FF output terminalFFOUT and start output terminal WU_Tx of the integrated circuit 300 aare respectively connected via the capacitors 403 to an FF inputterminal FFIN and AC start signal input terminal WU_RxAC of theintegrated circuit 300 b.

Similarly, a communication output terminal TXD, FF output terminalFFOUT, and start output terminal WU_Tx of the integrated circuit 300 bare respectively connected via the capacitors 403 to a communicationreceiving terminal RXD, FF input terminal FFIN, and AC start signalinput terminal WU_RxA of the integrated circuit 300 c corresponding tothe cell group one level above in the potential order. Moreover, acommunication output terminal TXD, FF output terminal FFOUT, and startoutput terminal WU_Tx of the integrated circuit 300 c are respectivelyconnected via the capacitors 403 to a communication receiving terminalRXD, FF input terminal FFIN, and AC start signal input terminal WU_RxACof the integrated circuit 300 d corresponding to the cell group onelevel above in the potential order, in other words, the cell group onthe highest potential side.

It is necessary to perform communication between the integrated circuit300 b connected to the cell group below the SD-SW 103 and the integratedcircuit 300 c connected to the cell group above the SD-SW 103 throughisolation. This is because if these communication lines are directlycoupled, the battery modules arranged above and below the SD-SW 103become connected in series through the connection. In this case, even ifthe SD-SW 103 is detached, the series connection between the batterymodules is maintained. Accordingly, the passage of electric current ofthe assembled battery 102 cannot be blocked. Therefore, if each cellgroup includes a large number of the single cells 101 and the voltageacross each cell group is high, a worker may receive an electricalshock. Hence, in the example of FIG. 2, the capacitors 403 are insertedbetween the integrated circuits 300 b and 300 c.

A communication output terminal TXD of the integrated circuit 300 dcorresponding to the cell group on the highest potential side isconnected via the high-speed insulating element 401 to a data receivingport RXD of the microcomputer 504. Similarly, an FF output terminalFFOUT and start output terminal WU_Tx of the integrated circuit 300 dare respectively connected via the low-speed insulating elements 402 toan FF signal input port and start signal input port of the microcomputer504.

The high-speed insulating elements 401 and the low-speed insulatingelements 402 used in the communication paths between the microcomputer504 and the integrated circuits 300 a and 300 d are collectivelyillustrated as the insulating element group 400 in FIG. 1.

An insulating element such as a photocoupler that can transmit DCsignals is used for the low-speed insulating element 402. Themicrocomputer 504 outputs a start signal being a DC signal from thestart signal output port to the DC start signal input terminal WU_Rx ofthe integrated circuit 300 a via the low-speed insulating element 402.The reason why the start signal is set to be a DC signal is because theinfluence of noise and a voltage change, which tend to occur at theactivation of the battery system 100, is removed.

If the start signal from the microcomputer 504 is input into the DCstart signal input terminal WU_Rx, the integrated circuit 300 a isactivated in response to this, and a start signal to activate the nextintegrated circuit 300 b is output. At this point in time, theintegrated circuit 300 a outputs an AC start signal from its startoutput terminal WU_Tx via the capacitor 403 to the AC start signal inputterminal WU_RxAC of the integrated circuit 300 b. For example, arectangular wave signal is output as the start signal.

If the start signal from the integrated circuit 300 a is input into theAC start signal input terminal WU_RxAC, the integrated circuit 300 b isactivated in response to the start signal, and a start signal toactivate the next integrated circuit 300 c is output as in the case ofthe integrated circuit 300 a. In other words, the integrated circuit 300b outputs the start signal being an AC signal from its start outputterminal WU_Tx via the capacitor 403 to the AC start signal inputterminal WU_RxAC of the integrated circuit 300 c. A similar operation isperformed also in the integrated circuit 300 c afterward.

If the start signal from the integrated circuit 300 c is input into theAC start signal input terminal WU_RxAC, and the integrated circuit 300 dis activated, a start signal is output from the start output terminalWU_Tx of the integrated circuit 300 d to the start signal input port ofthe microcomputer 504. If receiving the start signal, then themicrocomputer 504 can confirm the activation of the integrated circuits300 a to 300 d and recognize that the cell controller 200 has beenactivated.

After the activation of the cell controller 200, the microcomputer 504transmits a command signal and data (a data packet) to the receivingterminal RXD of the integrated circuit 300 a through the high-speedinsulating element 401. The integrated circuit 300 a receives thecommand signal and the data packet, and further transmits them from itsoutput terminal TXD to the next integrated circuit 300 b. In thismanner, all the integrated circuits 300 a to 300 d receive the commandsignal and the data to perform an operation in accordance with thecommand signal and the data. In order to obtain data such as the voltageacross each single cell 101 (referred to as the cell voltage) of thecell groups controlled respectively by the integrated circuits 300 a to300 d, each of the integrated circuits 300 a to 300 d adds data to thedata packet and transmits the data packet from its transmission terminalTXD to the RXD terminal of the next integrated circuit. The data packetis received by the data receiving port RXD of the microcomputer 504 inthe end. The microcomputer 504 receives the data packet containing thecommand signal that the microcomputer 504 itself transmitted.Accordingly, the microcomputer 504 confirms that the command signal hasbeen transferred normally and, if there is data added by the integratedcircuits 300 a to 300 d, receives the data.

The loop of an FF signal passing through the FF input terminals FFIN andFF output terminals FFOUT of the integrated circuits 300 a to 300 d is acommunication channel for detecting the overcharge or over-dischargestate of the single cell 101. This is for detecting overcharge in adifferent system from the communication line passing through the TXDterminal and the RXD terminal to improve the reliability of detection ofovercharge which is important to ensure the security of the single cell101 using a lithium-ion battery. The FF signal is assumed to be arectangular wave signal with a fixed cycle, and has, for example, arectangular wave of 1 kHz in the normal state, and a rectangular wave of2 kHz in the overcharge state.

If a rectangular wave of 1 kHz is input into the FF input terminal FFIN,the integrated circuit 300 recognizes that the integrated circuit 300 ata higher level in the communication order is in the normal state (notovercharged), and outputs a rectangular wave of 1 kHz to the FF outputterminal FFOUT. On the other hand, if the cell voltage detection valueof the integrated circuit 300 is detected to be an overcharge voltage,the integrated circuit 300 outputs a rectangular wave of 2 kHz to the FFoutput terminal FFOUT whether the frequency of the input signal of theFF input terminal FFIN is 1 kHz or 2 kHZ, and outputs the overchargestate to the next integrated circuit 300. Moreover, it is configured tonot output a rectangular wave from the FF output terminal FFOUT if thefrequency of the input signal of the FFIN terminal is a signal otherthan 1 kHz or 2 kHz.

Even if a certain integrated circuit 300 does not detect the overchargevoltage of the single cell 101 of the cell group controlled by theintegrated circuit 300, when another integrated circuit 300 inputs arectangular wave of 2 kHz into the FF input terminal FFIN, the relevantintegrated circuit 300 outputs a rectangular wave of 2 kHz to the FFoutput terminal FFOUT. In this manner, the FF signal loop outputs thatany of the integrated circuits 300 has detected overcharge.Consequently, the microcomputer 504 can detect overcharge from adifferent path from the high-speed communication signal loop.

The microcomputer 504 is configured to normally output a 1 kHzrectangular wave indicating the normal state as the FF signal to theintegrated circuit 300 a on the lowest potential side, putting theintegrated circuit 300 a at the highest level in the communicationorder. On the other hand, a 2 kHz rectangular wave indicating overchargeis required to be output when the operation of the FF loop is checked.In other words, even if all the integrated circuits 300 a to 300 d donot detect an overcharge voltage, as long as the rectangular wave of thereturned FF signal is 2 kHz, the microcomputer 504 can confirm that theFF loop is in normal operation. Moreover, if a trouble occurs in the FFloop, for example, if a wire has been broken, a rectangular wave is nottransmitted. Accordingly, the state can be identified.

The battery system according to the present invention described in theembodiment has features in the communication lines of start signals inthe integrated circuits 300 a to 300 d in the cell controller 200. FIG.3 is a diagram illustrating an example of communication connectionbetween the integrated circuits 300 a to 300 d in the cell controller200 and the microcomputer 504 in the battery controller 500 according toa conventional example, as a comparative example for describing thefeatures of the battery system of the present invention.

Comparing FIGS. 2 and 3, a difference is in that the communication linesof start signals between the integrated circuits 300 a to 300 d arerespectively connected via the capacitors 403 in FIG. 2 while beingcoupled via the low-speed insulating element 402 or directly coupled inFIG. 3. In other words, such a conventional example as illustrated inFIG. 3 is required to have such a connection form in order toinput/output start signals being DC signals between the integratedcircuits 300 a to 300 d.

The internal configuration of the integrated circuit 300 is described.FIG. 4 is a diagram illustrating an internal configuration example ofthe integrated circuit 300 according to the present invention. In FIG.4, it is configured that 12 single cells 101 (referred to as the cells 1to 12) constitute one cell group.

A cell group and the integrated circuit 300 that controls the cell groupare connected to CV terminals (terminals CV01 to CV12 and CV12N) forvoltage detection and BS terminals (terminals BS01H to BS12H andterminals BS01L to BS12L) for performing a balancing operation viavoltage detection lines L1P to L12P and L12N for detecting the voltagesof the cells 1 to 12. Both ends, that is, the positive and negativeelectrode terminals of each of the cells 1 to 12 are respectivelyconnected to the CV terminals via cell input resistors Rcv. A cell inputcapacitor Cin is connected between each CV terminal and a GND terminal.

Moreover, both ends of each of the cells 1 to 12 are respectivelyconnected to the BS terminals through balancing resistors Rb. In theintegrated circuit 300, balancing switches BSW for passing balancingcurrent are respectively connected between the terminals BS01H to BS12Hand the terminals BS01L to BS12L. If the balancing switch BSWcorresponding to any of the cells is turned on, the balancing current ofthe cell flows via the balancing resistors Rb. Balancing terminalcapacitors Cb are respectively connected between the BS terminals.

The CV terminals are connected to a multiplexer 210 in the integratedcircuit 300. The multiplexer 210 is for selecting an arbitrary cell andoutputting its positive and negative potentials, and is controlled inaccordance with an output from a logic unit 213. A differentialamplifier 211 converts the outputs of the multiplexer 210 into each ofthe voltages across the cells 1 to 12. An AD converter 212 then convertseach voltage into a digital value. The operation of the AD converter 212is controlled by the logic unit 213. The output of the AD converter 212is processed in the logic unit 213. In other words, the differentialamplifier 211 and the AD converter 212 measure voltage.

A multiplexer input short circuit switch MSW is provided between twovoltage input lines adjacent to each other, in other words, voltagedetection lines connected to a positive and a negative electrode of eachcell among voltage input lines connected to the multiplexer 210.

Auxiliary input terminals AUXIN and AGND are provided to the integratedcircuit 300. These auxiliary input terminals AUXIN and AGND areconnected to a thermistor 207, a thermistor dividing resistor Rthp, athermistor input resistor Rth, and a thermistor input capacitor Cth.

The resistance value of the thermistor 207 varies significantly with thetemperature of its installed location. The thermistor 207 and thethermistor dividing resistor Rthp in series divide the VDD voltage. Thevoltage across the thermistor 207 is input from the auxiliary inputterminals AUXIN and AGND into the integrated circuit 300. The thermistorinput resistor Rth and the thermistor input capacitor Cth act as an RCfilter that removes the noise of the input signal. In other words, thenoise of the voltage across the thermistor 207, the voltage changingdepending on temperature, is removed by the RC filter and the voltage isinput into the integrated circuit 300.

If the voltage across the thermistor 207 input into the integratedcircuit 300 is selected by the multiplexer 210, the voltage value isdigitized via the differential amplifier 211 and the AD converter 212.The digitized value of the voltage across the thermistor 207 is inputinto the logic unit 213.

The logic unit 213 transmits the digitized voltage across the thermistor207 as a data signal from the communication output terminal TXD via acommunication output unit 220. The data signal is transmitted to thebattery controller 500 via the above-mentioned communication line andaccordingly the digitized voltage across the thermistor 207 istransmitted. The battery controller 500 calculates the temperature ofthe location where the thermistor 207 is installed based on the voltageacross the thermistor 207. The temperature can be calculated using arelational expression between the voltage across the thermistor 207 andtemperature preset based on the resistance-temperature characteristic ofthe thermistor 207, or tabulated data of the relationship between thevoltage across the thermistor 207 and temperature.

A balancing switch state detection circuit 223 detects the presence orabsence of balancing current and diagnoses the balancing switch BSW.These results are output to the logic unit 213 and stored in a registerin the logic unit 213.

The logic unit 213 includes the register which stores data forcontrolling various switches provided to the integrated circuit 300. Forexample, data for selecting the input of the multiplexer 210, data forcontrolling the multiplexer input short circuit switch MSW, data forcontrolling the balancing switch BSW, and data for controlling a switchcircuit of the balancing switch state detection circuit 223 are storedin the register. A clock signal from an oscillation circuit 214 is inputinto the logic unit 213. The clock signal is used to operate the logicunit 213.

An operating power supply Vcc of the integrated circuit 300 is suppliedfrom a Vcc terminal connected to the voltage detection line L1P. Acapacitor Cvcc for suppressing noise is connected to the Vcc terminal.The voltage detection line L1P is connected to the positive electrodeside of the cell 1. The voltage at the positive electrode of the cell 1is supplied as the operating power supply Vcc to the integrated circuit300.

The Vcc terminal is further connected to a power supply unit 226 in theintegrated circuit 300. The power supply unit 226 includes a regulator227. The regulator 227 uses the operating power supply Vcc supplied fromthe Vcc terminal to generate an operating power supply VDD of 3.3 V andsupply it to the logic unit 213 and the like. The operating power supplyVDD is also supplied to a circuit outside the integrated circuit 300 viaa VDD terminal of the integrated circuit 300. A capacitor Cvdd forstabilizing operation is connected to the VDD terminal.

The power supply unit 226 includes also a starting circuit 228 whichoperates in response to a start detection signal from the startdetection unit 215. If an AC start signal from the integrated circuit300 at a lower level in the communication order is input into the ACstart signal input terminal WU_RxAC, or if a DC start signal from themicrocomputer 504 is input into the DC start signal input terminalWU_Rx, the start detection unit 215 detects the signal and outputs astart detection signal into the power supply unit 226. If the startdetection signal is input from the start detection unit 215, thestarting circuit 228 outputs the operating power supply Vcc to theregulator 227 and also activates the integrated circuit 300 to perform aPOR (power-on reset) operation. Diodes 216 being rectifying elements fordoubling and rectifying the voltage of the AC start signal andoutputting the start detection signal to the start detection unit 215are connected to the AC start signal input terminal WU_RxAC in theintegrated circuit 300.

If the integrated circuit 300 is activated, a start output unit 219operates with the output from the logic unit 213. The start output unit219 outputs an AC (rectangular wave) start signal from the start outputterminal WU_Tx to the integrated circuit 300 at a higher level in thecommunication order or the microcomputer 504.

The start detection unit 215 is connected to the Vcc terminal.Consequently, even while the operation of the entire integrated circuit300 is being suspended, the operating power supply Vcc is supplied tothe start detection unit 215. The start detection unit 215 has such acircuit configuration as to reduce the current consumed as much aspossible.

The communication output unit 220 outputs a command signal and data fromthe communication output terminal TXD to the integrated circuit 300 at ahigher level in the communication order or the microcomputer 504 basedon the output data from the logic unit 213. If the command signal anddata are input into the receiving terminal RXD from the integratedcircuit 300 at a lower level in the communication order or themicrocomputer 504, a communication receiving unit 217 receives thecommand signal and data to output them to the logic unit 213.

An FF output unit 221 outputs such an FF signal as described above fromthe FF output terminal FFOUT to the integrated circuit 300 at a higherlevel in the communication order or the microcomputer 504 based on theoutput data from the logic unit 213. If the FF signal is input into theFF input terminal FFIN from the integrated circuit 300 at a lower levelin the communication order or the microcomputer 504, the FF input unit218 receives the FF signal, determines which of the normal state and theovercharge state the FF signal represents, and outputs the determinationresult to the logic unit 213.

The internal configuration of the integrated circuit 300 according tothe conventional example is described as a comparative example. FIG. 5is a diagram illustrating an internal configuration example of theconventional integrated circuit 300 used to input/output a start signalbeing a DC signal in the connection example illustrated in FIG. 3.

Comparing FIGS. 4 and 5, the integrated circuit 300 of FIG. 5 isprovided with terminals CP+ and CP− connected to a charge pump unit 238and a charge pump capacitor Ccp. The charge pump unit 238 in theintegrated circuit 300 generates charge pump voltage using the operatingpower supply Vcc in cooperation with the charge pump capacitor Ccpconnected to the outside of the integrated circuit 300, and supplies thecharge pump voltage to the start output unit 219. In the conventionalexample, such a circuit is required to output a start signal at a highervoltage than the operating power supply Vcc in accordance with thepotential of the cell group corresponding to the integrated circuit 300of an output destination.

Moreover, the integrated circuit 300 of FIG. 5 does not include the ACstart signal input terminal WU_Rx of FIG. 4 for receiving an AC startsignal, and the diodes 216.

FIG. 5 illustrates the internal configuration example of the integratedcircuit 300 of the case of the connection example illustrated in FIG. 3,in other words, the case where DC start signals are input/outputsequentially from the lowest potential side in the communication orderopposite to the potential order of the assembled battery 102. However,contrary to this, DC start signals may be input/output sequentially fromthe highest potential side in the same communication order as thepotential order of the assembled battery 102. In this case, a startsignal at a higher voltage than the operating power supply Vcc is inputinto the start detection unit 215 in accordance with the potential ofthe cell group corresponding to the integrated circuit 300 which hasoutput the start signal. Hence, the need of the charge pump unit 238 andthe charge pump capacitor Ccp is eliminated. However, it is necessary toprovide an interface circuit, a protection circuit, and the like insteadto enable the start detection unit 215 to operate normally even if ahigh voltage start signal is input.

A description is given in detail of the input/output of start signalsbetween the integrated circuits 300 a to 300 d and the microcomputer 504of FIG. 2. FIG. 6 is a diagram illustrating a detailed example ofcommunication connection between the integrated circuit 300 a on thelowest potential side, the integrated circuit 300 b one level above theintegrated circuit 300 a in the potential order, and the microcomputer504 in FIG. 3. Moreover, FIG. 7 is a diagram illustrating the detailedexample of communication connection between the integrated circuit 300 don the highest potential side, the integrated circuit 300 c one levelbelow the integrated circuit 300 d in the potential order, and themicrocomputer 504 in FIG. 3.

In FIG. 6, the integrated circuit 300 a on the lowest potential side isat the highest level in the communication order. In the integratedcircuit 300 a, the DC start signal input terminal WU_Rx is used to inputa DC start signal output from the microcomputer 504. A photocoupler isconnected as the low-speed insulating element 402 to this terminal. Themicrocomputer 504 passes current through a diode of the photocoupler viaa drive transistor 404, which turns on a transistor side insulated fromthe diode in the photocoupler. The transistor is connected on itscollector side to Vcc of the integrated circuit 300 a via a resistor,and connected on its emitter side to a ground via a resistor. When thetransistor side of the photocoupler is turned on, a voltage obtained bydividing Vcc by the resistor is applied to the DC start signal inputterminal WU_Rx of the integrated circuit 300 a. The start detection unit215 is a comparator including a preset threshold value, and outputs astart detection signal to the power supply unit 226 (see FIG. 4) ifdetecting a voltage equal to or more than the threshold value.Consequently, the integrated circuit 300 a is activated.

If the integrated circuit 300 a is activated as described above, thestart output unit 219 of the integrated circuit 300 a outputs an ACstart signal from the start output terminal WU_Tx at the instruction ofthe logic unit 213. It is assumed here that a rectangular wave signal isoutput as the AC start signal. The signal is applied through thecapacitor 403 to the AC start signal input terminal WU_RxAC of theintegrated circuit 300 b that is one level above in the potential orderand one level below in the communication order.

In the integrated circuit 300 b, the AC start signal input terminalWU_RxAC is connected to the diodes 216 connected between the ground andthe DC start signal input terminal WU_Rx. The diodes 216 and thecapacitor 406 connected between the DC start signal input terminal WU_Rxand the ground are part of the components of the doubler rectifiercircuit. If being input into the AC start signal input terminal WU_RxACin the integrated circuit 300 b, the rectangular wave signal as the ACstart signal output from the integrated circuit 300 a is rectified bythe doubler rectifier circuit and converted into DC voltage. The DCvoltage is input into the start detection unit 215 and accordingly astart detection signal is output from the start detection unit 215 toactivate the integrated circuit 300 b.

The diodes 216 are connected between the ground and the DC start signalinput terminal WU_Rx also in the integrated circuit 300 a, and areconnected to the AC start signal input terminal WU_RxAC. However, the DCstart signal from the microcomputer 504 input into the DC start signalinput terminal WU_Rx of the integrated circuit 300 a is input into thestart detection unit 215 not via the diodes 216. Hence, the DC startsignal can be detected by the start detection unit 215.

FIG. 8 illustrates apart related to the communication path of an ACstart signal between the integrated circuits 300 a and 300 b in areadily understandable manner. Within the part, FIG. 9 is an equivalentcircuit diagram corresponding to the cell group connected to the diodes216, the capacitor 403 connected between the start output terminal WU_Txof the integrated circuit 300 a and the AC start signal input terminalWU_RxAC of the integrated circuit 300 b, the capacitor 406, and theintegrated circuit 300 a. The circuit illustrated in FIG. 9 is a generaldoubler rectifier circuit. If a rectangular wave signal with anamplitude VDD is output from the start output terminal WU_Tx of theintegrated circuit 300 a, a fixed DC voltage Vw is applied by thedoubler rectifier circuit to the start detection unit 215 of theintegrated circuit 300 b.

FIG. 10 illustrates a voltage waveform example of a rectangular wavesignal with the amplitude VDD output from the start output terminalWU_Tx of the integrated circuit 300 a, and the DC voltage Vw applied tothe start detection unit 215 of the integrated circuit 300 b. In FIG.10, the left vertical axis represents the voltage values of arectangular wave signal, and the right vertical axis represents thevoltage values of DC voltage. As illustrated in the example, if arectangular wave signal at a frequency of 32 kHz and an amplitude of 3.3Vp-p is output as the AC start signal from the integrated circuit 300 a,a DC voltage of approximately 2.5 V is applied to the start detectionunit 215 of the integrated circuit 300 b. The DC voltage rises up to avoltage equal to or more than approximately 90% in approximately 0.1 msafter the start of the output of the rectangular wave. Consequently, itcan be seen that the starting time from the output of the AC startsignal by the integrated circuit 300 a to the activation of theintegrated circuit 300 b is sufficiently short. The capacity of thecapacitor 406 is set to 0.01 μF.

Return to the description of FIG. 6. In the integrated circuit 300 a ofFIG. 6, a digital isolator using, for example, a small transformer forcommunication as the high-speed insulating element 401 is connected tothe communication receiving terminal RXD connected to the communicationreceiving unit 217. A command and communication data which aretransmitted from the microcomputer 504 are input into the communicationreceiving unit 217 from the communication receiving terminal RXD of theintegrated circuit 300 a through the digital isolator. The VDD terminalof the integrated circuit 300 a supplies the operating power supply VDDto the digital isolator. The operating power supply VDD is not outputduring the suspension of the operation of the integrated circuit 300 a.Therefore, dark current does not flow through the digital isolator atthis point in time.

Moreover, a photocoupler is connected as the low-speed insulatingelement 402 to the FF input terminal FFIN connected to the FF input unit218 of the integrated circuit 300 a as in the case of the DC startsignal input terminal WU_Rx. The microcomputer 504 passes currentthrough a diode of the photocoupler via a drive transistor 405.Accordingly, a transistor side insulated from the diode in thephotodiode is turned on to transmit an FF signal.

In FIG. 7, the integrated circuit 300 d on the highest potential side isat the lowest level in the communication order. The AC start signal of arectangular wave output by the start output unit 219 of the integratedcircuit 300 d from the start output terminal WU_Tx is input into thestart signal input port of the microcomputer 504 via a drive transistor409 and a photocoupler being the low-speed insulating element 402. Ifreceiving the AC start signal output from the integrated circuit 300 d,then the microcomputer 504 can confirm that all the integrated circuits300 a to 300 d have been activated.

Moreover, the command and communication data output by the communicationoutput unit 220 of the integrated circuit 300 d from the communicationoutput terminal TXD are input into the data receiving port RXD of themicrocomputer 504 via a digital isolator being the high-speed insulatingelement 401. The VDD terminal of the integrated circuit 300 d suppliesthe operating power supply VDD to the digital isolator. Furthermore, theFF signal output by the FF output unit 221 of the integrated circuit 300d from the FF output terminal FFOUT is input into the FF signal inputport of the microcomputer 504 via a drive transistor 410 and aphotocoupler being the low-speed insulating element 402. Themicrocomputer 504 may confirm that all the integrated circuits 300 a to300 d have been activated by receiving them from the integrated circuit300 d.

The embodiment described above has the following operations and effects.

(1) The battery monitoring and control integrated circuit 300 isconfigured by the diodes 216, the capacitor 403, and the capacitor 406,and includes the AC start signal input terminal WU_RxAC for connectingto the doubler rectifier circuit which generates a DC signal based on anAC start signal input from the integrated circuit 300 at a higher levelin the communication order connected via the capacitor 403, the startdetection unit 215 which detects the DC signal and activates therelevant integrated circuit 300, and the start output unit 219 whichoutputs the AC start signal to the integrated circuit 300 at a lowerlevel in the communication order or the microcomputer 504 of the batterycontroller 500 after the activation of the relevant integrated circuit300. Consequently, compared with the conventional case using a DC startsignal, it is not necessary for the integrated circuit 300 to include acharge pump circuit for outputting a start signal at a higher voltagethan the operating power supply Vcc, and an interface circuit, aprotection circuit, and the like for enabling the start detection unit215 to operate normally even if a high voltage start signal is input.Therefore, the need of special circuits to input/output a start signalcan be eliminated.

(2) The doubler rectifier circuit includes the diodes 216 built in theintegrated circuit 300. Hence, the doubler rectifier circuit can easilybe configured by connecting capacitors with an appropriate capacity asthe capacitors 403 and 406 outside the integrated circuit 300.

(3) The integrated circuit 300 further includes the DC start signalinput terminal WU_Rx for inputting a DC start signal input from themicrocomputer 504. The DC start signal input into the DC start signalinput terminal WU_Rx is input into the start detection unit 215 not viathe doubler rectifier circuit. Hence, the DC start signal can bedetected in the start detection unit 215 in a similar detection methodto that of the AC start signal input via the doubler rectifier circuit.

An example of the embodiment of the present invention has been describedabove. However, the present invention is not limited to this. Thoseskilled in the art can make various modifications without impairing thefeatures of the present invention.

For example, in the embodiment, a start signal, a command andcommunication data, and an FF signal are transmitted between theintegrated circuits 300 in the communication order opposite to thepotential order of the assembled battery 102. However, the communicationorder may be reversed. In other words, a start signal, a command andcommunication data, and an FF signal can be transmitted between theintegrated circuits 300 also in the same communication order as thepotential order of the assembled battery 102. In the present invention,all of these signals are transmitted between the integrated circuits 300via the capacitors 403. Accordingly, the relationship between thepotential order and the communication order is not particularly limited.

Moreover, the communication signal and FF signal, which are described inthe embodiment, may be differential signals to make resistant to noise.Furthermore, an AC start signal of a rectangular wave or the like may beoutput from the battery controller 500, and input into the AC startsignal input terminal WU_RxAC of the integrated circuit 300 at thehighest level in the communication order. Alternatively, a start signaland communication signal or FF signal from the battery controller 500may be shared. Communication signals and FF signals are transmitted fromthe battery controller 500 all the time during the operation of thebattery controller 500. Hence, it is possible to generate a DC signalfrom these signals and use the DC signal as a start signal in theintegrated circuit 300.

Various modifications described above may be applied individually or maybe freely combined to be applied.

The scope of the present invention is not limited to a battery systemhaving the configuration described in the embodiment. The presentinvention can be applied to battery systems having variousconfigurations, and to electrically driven vehicles having variousspecifications.

The invention claimed is:
 1. A battery monitoring and control integratedcircuit which is connected to a cell group having a plurality ofseries-connected single cells, and which monitors and controls thesingle cells, the battery monitoring and control integrated circuitcomprising: a signal input terminal for inputting an AC signal; a DCsignal generation circuit which generates a DC signal based on the ACsignal; and a start detection unit which detects the DC signal andactivates the battery monitoring and control integrated circuit; wherebythe DC signal is for activating the battery monitoring and controlintegrated circuit.
 2. The battery monitoring and control integratedcircuit according to claim 1, wherein the DC signal generation circuitis a doubler rectifier circuit.
 3. The battery monitoring and controlintegrated circuit according to claim 2, wherein the doubler rectifiercircuit includes a rectifying element built in the battery monitoringand control integrated circuit.
 4. The battery monitoring and controlintegrated circuit according to claim 1, further comprising a secondinput terminal for inputting a second DC signal, wherein the second DCsignal is input into the start detection unit not via the DC signalgeneration circuit.